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Date: Wed, 18 Mar 2009 08:41:44 -0400
From: Charles Wilson <cygwin AT cwilson DOT fastmail DOT fm>
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To: cygwin AT cygwin DOT com
Subject: Re: _set_fmode?
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Corinna Vinschen wrote:
> On Mar 17 21:15, Charles Wilson wrote:
>>
>> +#if defined(_WIN32) && !defined(__CYGWIN__)

> The !defined(__CYGWIN__) is not necessary because gcc for Cygwin
> doesn't define _WIN32.

gcc does not define it. But the w32api headers DO.

/usr/include/w32api/windef.h:
#ifndef WIN32
#define WIN32
#endif
#ifndef _WIN32
#define _WIN32
#endif

So, if you #include windows.h, you'll have _WIN32 defined. If your code
needs to do different stuff on "real" win32 and cygwin, then you need
this kind of #if _WIN32 && !CYGWIN magic. libarchive fits this category,
because even the cygwin port uses some win32 calls (there's special code
to check if you have "root"-ish permissions, which looks up SIDs and
checks your group memberships...)

>   extern int _fmode;
>   _fmode = O_BINARY;

I didn't know you could access it directly, outside of cygwin1.dll.

> _fmode is defined in crt0.o so you can simply access it if you like.
> But anyway, using binmode.o is much more elegant, IMHO.  I don't see
> what speaks against using it.

Well, now that I see libbinmode.a, nothing.

But using /usr/lib/binmode.o in your build rules is non-portable, and
breaks cross-compiles (my linux box doesn't have that file, and even if
it did it wouldn't be cygwin's).  gcc doesn't search the -L path for
.o's, so you can't just specify 'binmode.o', you have to give the full
path.  So I was stuck with a patch that would not be acceptable
upstream, to explicitly add "/usr/lib/binmode.o" to the LDADD variable
with an AM_CONDITIONAL on $host=cygwin. Ugly.

At least now, I see that I can use an AM_CONDITIONAL to add -lbinmode to
LDADD, which is much cleaner and actually works on cross builds.

--
Chuck


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